Technical Field
The present invention relates to a photoconductor, an image forming method utilizing the photoconductor, a method of manufacturing the photoconductor, and an image forming apparatus.
Background Art
In general, image forming apparatuses such as printers, photocopiers, facsimile machines which employ electrophotography form images through a series of processes of charging, irradiating, developing, transferring, and cleaning. The devices to conduct such image forming include at least a charger, an image irradiator, a developing device (reverse developing device), a transfer device, a cleaner, and an image bearing member (photoconductor). Image forming apparatuses having this kind of configuration are not free from problems of degradation of output images caused by blackened surface of the photoconductor during a long period of continuous use. When such background fouling occurs, the photoconductor is replaced with a fresh one. To meet increasing attentions for reduction of print cost and improvement of environmental performance, a photoconductors with further improved durability have been demanded.
Cleaning blades are popular as cleaning members used as cleaning devices for image forming apparatuses. A cleaning blade is formed by fixing a molded rubber blade having a plate-like form to a substrate such as an aluminum plate or iron plate. The edge of the blade is provided to be in contact with a photoconductor under constant load (pressure).
The blade edge is normally arranged in such a manner that the blade edge contacts a photoconductor in a counter direction (in which the blade edge bites into the photoconductor during rotation thereof, that is, the direction reversing to the rotation direction) in terms of cleaning property. The cleaning blade for use in this counter method is preferably formed of elastic materials, which easily imparts deflection rigidity to the cleaning blade. For example, when a photoconductor having a drum form is used, the cleaning blade is arranged in the counter direction to the drive (rotation) direction of the photoconductor with an angle θ to contact the photoconductor. Furthermore, the cleaning blade is pressed against the photoconductor in such a manner that the edge of the cleaning blade bites into the photoconductor to scrape off toner remaining on the surface of the photoconductor.
However, if the friction coefficient of the surface of the photoconductor increases under the contact conditions, the front edge surface of the cleaning blade is dragged and stretched so that a space having a wedge-like form appears between the stretched position and the surface of the photoconductor. The edge of the blade is dragged by the photoconductor and deformed like a wedge-like form. When the toner accumulates in the wedge-like space, the edge reacquires the original position by the elastic restoring force to stress occurring when the edge of the blade is dragged and deformed by the photoconductor. This is referred to as stick slip motion. When the photoconductor is driven in an image forming apparatus, the cleaning blade in contact with the photoconductor is more or less pulled into the drive direction of the photoconductor, which triggers stick slip motion.
The mechanism of this slip stick motion is inferred that at the point when the restoring force due to elasticity of a cleaning blade surpasses the maximum static frictional force thereof against a photoconductor, the cleaning blade moves in the restoring direction at once and thereafter moving of the cleaning blade stops as the restoring force is reduced and again is dragged in the drive direction. Unless this slip stick motion is stabilized in particular for an image forming apparatus for wide recording media for use in photocopying of design drawing, toner slips through the blade, which leads to occurrence of background fouling ascribable to cleaning performance so that it is inevitable that parts are replaced with fresh ones frequently.